Aeroelastic eigenvalue analysis of a variable speed rotor blade with an applied compressive load

Robert Dibble, Vaclav Ondra, Benjamin King Sutton Woods, Branislav Titurus

Research output: Chapter in Book/Report/Conference proceedingConference Contribution (Conference Proceeding)

5 Citations (Scopus)
224 Downloads (Pure)


Variable speed rotors are one possible way to meet the industry’s increasing demands on noise emissions, flight envelopes and power requirements. The use of this technology is largely prohibited due to the presence of dynamic interactions at various rotor speeds that would lead to excessive vibratory loads. One concept being considered to overcome this is modal tuning by means of an applied compressive load. Herein, the impact of the combined effects of compressive loading, aerodynamic loading in hover and reduced rotor speeds on rotor blade’s aeroelastic properties are investigated. A structurally nonlinear blade model directly coupled with an unsteady aerodynamic blade element model is formulated and verified. The model is used to show that moderate static deformations due to aerodynamic loads can introduce stiffening as well as softening effects. Compressive loading is then applied and it is shown that even at large compressive loads the blade’s internal tension remains dominated by centrifugal loading. Finally, a study of the change in natural frequencies and damping ratios at various rotor speeds and compressive loadings is performed. It shows that natural frequencies and damping ratios are both affected by changing rotor speed and compressive load and that the sensitivity to the compressive load is greatest at lower rotor speeds.

Original languageEnglish
Title of host publicationAIAA Scitech 2019 Forum
PublisherAmerican Institute of Aeronautics and Astronautics Inc. (AIAA)
ISBN (Print)9781624105784
Publication statusPublished - 6 Jan 2019
EventAIAA Scitech Forum, 2019 - San Diego, United States
Duration: 7 Jan 201911 Jan 2019

Publication series

NameAIAA Scitech 2019 Forum


ConferenceAIAA Scitech Forum, 2019
Country/TerritoryUnited States
CitySan Diego
Internet address


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